For Thais, the recipe for a puffy fried omelet is almost too basic to say. It's made from ingredients that all Thai people have in their fridge or pantry—eggs, sugar, fish sauce, herbs, and ground pork or crab if you want—and if you cook at all, then of course you can make it. Even if a restaurant doesn't list it on its menu, it's assumed that it can be whipped up at any time. The texture of this style of egg is almost like a frittata more than a traditional omelet, though you do achieve that same fluffy-inside effect but with the added bonus of crispy browned edges. The technique is essentially a shallow-fry, which causes the eggs to puff up as they quickly cook.
Using pork and/or crab can add richness, but ultimately they're optional. This is just as good without any type of meat. I find that including some sort of onions or shallots adds body, but if you wanted to go even simpler you could always make the omelet with just eggs.
In a small bowl, beat the eggs with the fish sauce, then fold in the sugar, red onion, crab or pork, and a pinch of white pepper.
Heat an empty wok over high heat until it begins to smoke, then swirl in the oil. Once the oil is shimmering, pour in the egg mixture using one swift motion. You're basically making a deep-fried egg pancake, so the oil should be hot and plentiful. The egg will crackle and sizzle at first, but after about 20 seconds it will have died down enough that you can flip it over. Don't worry about executing the perfect flip; this isn't meant to be a flawless French omelet. Cook the other side for 20 seconds or so, until golden, then remove it from the pan and let it briefly drain on a paper towel. Garnish with herbs, if desired, and serve Sriracha on the side.
A note on ground pork: Thai-style is to mix it into the egg raw so that it cooks together with the egg (bring the raw pork to room temperature first). If you're worried about undercooked pork, you can also parcook the meat beforehand.